INVESTMENTS - Contractual Maturities of Investments in Fixed Maturities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Held to maturity:
Total fixed maturities held to maturity, amortized cost	$ 33,459	$ 34,242
Held to maturity:
Total fixed maturities held to maturity, fair value	37,520	$ 38,497
Aflac Japan
Available for sale:
Due in one year or less	130
Due after one year through five years	2,617
Due after five years through 10 years	11,543
Due after 10 years	33,608
Mortgage- and asset-backed securities	372
Total fixed maturities available for sale, amortized cost	48,270
Held to maturity:
Due in one year in less	316
Due after one year through five years	1,692
Due after five years through 10 years	1,613
Due after 10 years	29,802
Mortgage- and asset-backed securities	36
Total fixed maturities held to maturity, amortized cost	33,459
Available for sale:
Due in one year or less	142
Due after one year through five years	2,984
Due after five years through 10 years	11,642
Due after 10 years	37,112
Mortgage- and asset-backed securities	424
Total fixed maturities available for sale, fair value	52,304
Held to maturity:
Due in one year or less	320
Due after one year through five years	1,775
Due after five years through 10 years	1,732
Due after 10 years	33,655
Mortgage- and asset-backed securities	38
Total fixed maturities held to maturity, fair value	37,520
Aflac U.S.
Available for sale:
Due in one year or less	23
Due after one year through five years	648
Due after five years through 10 years	2,105
Due after 10 years	9,049
Mortgage- and asset-backed securities	35
Total fixed maturities available for sale, amortized cost	11,860
Held to maturity:
Due in one year in less	0
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	0
Mortgage- and asset-backed securities	0
Total fixed maturities held to maturity, amortized cost	0
Available for sale:
Due in one year or less	24
Due after one year through five years	709
Due after five years through 10 years	2,177
Due after 10 years	9,569
Mortgage- and asset-backed securities	43
Total fixed maturities available for sale, fair value	12,522
Held to maturity:
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	0
Mortgage- and asset-backed securities	0
Total fixed maturities held to maturity, fair value	$ 0